The common shelduck (Tadorna tadorna) belongs to the ducks, but in shape it is more similar to a goose. It has a chunky body and long legs, neck and head. The wingspan measures from 100 to 120 cm, and when fully extended it is 55 to 65 cm long, thus somewhat larger than our most common duck – the mallards. The common shelduck is very distinctive and strikingly colored. Predominant color is white – the lower part of its neck, belly, flanks, tail and the front part of the wing are white. Its head is dark green, its chest is adorned with a broad brown band. It has a bright red bill, and the legs are rather dull red. Males can be recognized by the red crest above the bill, which females do not have, and the latter are also somewhat smaller.
This is an omnivorous, diurnal species. It feeds on marine mollusks, in inland (freshwater) waters the main part of its diet consists of other invertebrates, for example insects, crayfish, and also vertebrates – mainly small fish. In shallow water they search for algae and other aquatic vegetation, they also like to graze on grassy shores of large rivers and lakes, and also in fields there are plenty of seeds they cannot resist.
Most populations of the common shelduck migrate, however the birds living in Europe stay in the same area more or less all year round. They are therefore residents, which the harshest frost drives south. In Slovenia these colorful birds are irregular visitors, which can be observed here and there throughout the year. For nesting areas they prefer saline wetlands, for example the coastal area with mud flats and muddy or sandy river outlets, but they also nest on the shores of steppe lakes and rivers. Common shelducks are interesting also because they nest in tree cavities or in burrows dug by mammals. On the ground they rarely build a nest.
The species is especially threatened by the loss of suitable habitat due to changes in the tidal regime. Additionally, nesting birds are under great pressure due to predation by the non-native mink – the American mink (Neovison vison), which escaped from a farm where it is kept for its valuable fur.
